Corrected the Makefile, which was using the "exclude" option on the
standard cell verilog that was supposed to be used on the standard
cell LEF.  Mostly all this does is to change the nature of the error
that occurs.  Ultimately the source of the LEF files needs to be
fixed, which will happen eventually.  Also corrected the generate()
routine in soc_floorplanner.  This fixes the behavior in which
clicking on the "Generate" button in the floorplanner app causes
an error.
diff --git a/sky130/magic/sky130.tech b/sky130/magic/sky130.tech
index 4da410e..1bbf877 100644
--- a/sky130/magic/sky130.tech
+++ b/sky130/magic/sky130.tech
@@ -3446,6 +3446,10 @@
 
 lef
 
+ masterslice pwell  substrate
+ masterslice nwell  nwell
+ masterslice poly   poly
+
  routing li	li1 LI1 LI li
 
  routing m1	met1 MET1 m1